The present invention provides novel polycarbonate modified epoxy resins, as well as cured compositions prepared from said epoxy resins.
Conventional advancement chemistry, wherein an epoxy resin, such as a diglycidyl ether of bisphenol A, and a polyphenol, such as bisphenol A, are reacted provides advanced epoxy resins which are useful to prepare cured (thermoset) products. Although this advancement reaction provides a useful product, it also consumes epoxide groups while increasing molecular weight, thus decreasing curability, reactivity, corrosion resistance, crosslink density in the cured product, and the like.
The present invention provides polycarbonate modified epoxy resins which possess a substantially increase epoxide content per unit molecular weight thus restoring curability, reactivity, corrosion resistance, crosslink density in the cured product, and the like while simultaneously maintaining the benefits of higher molecular weight, notably increased mechanical strength. Enhanced adhesion to metal and resistance to cathodic disbondment are obtained with cured powder coating compositions prepared from the polycarbonate modified epoxy resins of the present invention.